No can do, the AC Commander has different code to manage the different type motor, they are not interchangeable even with the added bridge rectifier. They used the same PCB, but you'd have to have the code changed as well. Since only Lionel can change that code, and I really doubt they'll be willing, just buy a Cruise Commander.
The DC can motor that Timko uses isn't a very large motor as it wouldn't fit inside the shell, so I would question the torque improvement. However, it does make a much nicer running unit, I have one upgraded with the Timko motor and fan driven smoke. Given the fact that it has no traction tires, I figure the wheels will slip before the smaller motor runs out of torque. 
